“So this could go very well or very badly.”

After surviving being taken over by the Monks, “Doctor Who’s” time-traveling duo are heading off planet to see about some aliens this time.

On Saturday’s all-new episode titled “Empress of Mars,” Bill (Pearl Mackie) and the Doctor (Peter Capaldi) have gone back to the Victorian era and have seen something puzzling: Someone has scrawled, “God Save the Queen” on the surface of Mars. The problem is that humans really haven’t achieved space travel, much less reached another planet this early in history. Or so we think.

Naturally, the Doctor and Bill hop in the TARDIS to go investigate. Heading to Mars has its problems though because that’s where the Ice Warriors dwell. These reptilian humanoids wear full armor, which is partly cybernetic, and of course they put the “war” in warrior. BBC America offers up some clues in the photo gallery seen above or here.

In the sneak peek clip, the Doctor faces off with an advancing Ice Warrior and things could “go very well or very badly.” Bill, on the other hand, has come face-to-helmet with… we’re not sure who. Any guesses? Take a look at the trailer for Saturday’s episode and then the clip below:

The episode was written by Mark Gattis, who had previously written about the return of the Ice Warriors in the submarine adventure episode “Cold War.” He’s also responsible for the gothic but entertaining episode “The Crimson Horror” and the atrocious “Robot of Sherwood.” He is Steven Moffat’s partner on “Sherlock,” on which also plays brother Mycroft Holmes.